Many have studied the effects of stress and other stimuli on the human body for years. Most refer to stress as a state of mental, emotional, or other psychological strain placed upon one's body. In reality, stress can be any substance or occurrence that places an undue tension or strain on one's physiological and psychological state. A simplistic example is a body's response to the common cold. As a person is exposed to and contracts the common cold virus, the virus will multiply and challenge the body's normal functions by placing an undue stress upon the body. Once the virus is eliminated, the body may return once again to its steady state or normal state. Similarly, emotional disturbances can lead to serious stress responses, often greater than physiological ones. There have been many who have developed methods and devices for analyzing the affects of stress on the human body. Specifically, most have focused on the affects of mental strains or stresses, however, others have focused specifically on physiological stresses.
Around 1950, Dr. Voll, a German doctor studied the electrical properties of acupuncture points and how these properties change as a reflection of stress on the body. Dr. Voll believed that the body responds in a measurable way to stresses that are momentarily placed in proximity to the body. In particular, acupuncture points are situated along acupuncture meridians within a subject's body. The meridians are energetic pathways that traverse along a subject's body. It is believed that acupuncture points relate to various organs and body systems and are more electrically sensitive than surrounding tissue. Measuring the activity around the acupuncture points can help predict whether problems are occurring or will occur within a subject and possibly which bodily organs will be affected.
Other methods and devices for measuring physiological parameters of individuals have been utilized for many years. For example, Galvanic Skin Response (GSR) devices, also known as electrodermal response (EDR), have been used to obtain biofeedback from individuals. Specifically, GSR measures the electrical resistance of the skin and interprets the measurements as an image of activity in certain parts of the body, i.e. biofeedback. Those who have studied human galvanic skin responses believe the more relaxed a person is, the dryer the person's skin will be, thus the higher the skin's electrical resistance will be. When a person is under stress the hand sweats and the resistance goes down. This process has been commonly used in psychophysiology experiments to infer the emotional state of a subject and has also been used in lie detectors, i.e. polygraph devices.
Other known devices have been devised to test specific physiological parameters of a person, such as electroencephalogram (EEG) machines. The EEG machines have been designed to monitor the brain wave activity of a patient. Additionally, some devices measure skin temperature which can be helpful in detecting certain circulatory disorders. Another machine commonly used is an electromyogram (EMG) machines which measures muscle tension in a living subject. Other devices have been employed to monitor heart rate and blood pressure, both of which change in response to stress, arrhythmia and hypertension. As previously mentioned, a lot of emphasis has been placed on monitoring anxiety states of people. These measurements can be adapted in lie detector devices to determine whether a person is telling the truth.
These previous devices have attempted to measure specific physiological parameters but have been met with varying degrees of success. One major down fall is the devices are tailored for measuring a specific physiological parameter. Yet, they offer no real solution for evaluating the physiological measurements or patterns and how it affects a person. For example, most methods and devices are not diverse in its measurements and teach measuring only a specific location for measuring the parameters, i.e. the face. Others believe obtaining biofeedback data can help you train body to over come certain disabilities, i.e. mind over matter.
As such, devices and methods that measure and evaluate stress responses in a living subject thereby providing the subject with beneficial information continues to be sought through ongoing research and development efforts.